MAPLE syrup disease is a rapidly progressive familial cerebral degenerative condition marked by the excretion of a urine possessing a sweet, maple syrup-like odor.1 The enzymatic basis for this disease is a failure in the oxidative decarboxylation of three branched-chain keto acids, the derivatives of leucine, valine, and isoleucine. As a consequence of the defect, these compounds and their amino acid analogues are excreted in large amounts, and plasma levels of branched-chain amino acids are many times higher than normal.2 Hypertonia, disturbances in respiration, and seizures appear shortly after birth and prove to be fatal within a few weeks or months in a majority of children.
In analogy to the therapy for phenylketonuria, Holt et al first suggested regulating the abnormal blood levels of branchedchain amino acids by means of a completely synthetic diet in which the intake of leucine, isoleucine, valine, and methionine could be carefully
Menkes JH, Solcher H. Maple Syrup DiseaseEffects of Dietary Therapy on Cerebral Lipids. Arch Neurol. 1967;16(5):486–491. doi:10.1001/archneur.1967.00470230038004